advertisement
Abstract #10351 Published in IGR 6-1
Temporal dynamics and magnitude of the blood flow response at the optic disk in normal subjects during functional retinal flicker-stimulation
Riva CE; Logean E; Falsini BNeuroscience Letters 2004; 356: 75-78
Near-infrared laser Doppler flowmetry was applied in 15 normal volunteers to record the time course and magnitude of changes in the velocity (Vel), volume (Vol) and flow (F) of blood and tissue reflectance (R) at the optic disc in response to 40 and 50 seconds of increased retinal neural activity. This activity was evoked by diffuse luminance flicker of the retinal posterior pole. After 20 seconds of flicker, the group averages of Vel, Vol, and F were significantly higher than at baseline (pre-flicker) by 12, 24 and 38%, respectively. Time constants of the increases in Vel, Vol, and F were 3.4, 12.7 and 9.1 seconds, respectively. The group average change in R of 1% was not significant. However, in one subject, 15 recordings from the same site of the optic disc showed a significant increase in R of 8%, with a time course similar to that of Vol. These findings show that, in the human optic nerve, a white matter tissue, the temporal dynamics and magnitude of the response of blood flow to an increase in retinal neural activity are similar to those reported for brain gray matter. Furthermore, although the R-response could be due, in part, to changes in blood volume, other factors, such as activity-evoked tissue scattering changes, may also affect this response.
Dr. C.E. Riva, Inst. de Recherche en Ophtalmologie, 64 Avenue Grand Champsec, 1950 Sion, Switzerland
Classification:
6.11 Bloodflow measurements (Part of: 6 Clinical examination methods)
